Haiz... some ppl just come here, throw a question and expect an answer without bother giving details.
rather ask them go read stickie.

oh gosh...
protein is to repair ur muscles (if u workout)
taking protein while sitting at home doesn't benefit u if u dont workout.
weight gainer( the name tells it all)

my suggestion since u r underweight.
eat a lot and if u can afford weight gainer go for it.
once u reach a stage where u think u dont need weight gainer, then u can stop it and get whey. good luck

whey is protein.
go find out wat protein does for ur muscles. =.=

taste wise, ON is slightly better, price also slightly higher.
if u r particular bout taste, then willing to spend, then by all means, go ahead with ON. if not, scivation aint too bad itself.
i would rather spend less but eat more.

hahaha....

u should bulk up to at least 70kg.
gaining weight is not easy for u ecto.
suggestion is, eat as much as u can.
supplement? if got money, then u better buy more solid food.
but weight gainer aint too bad of a choice either.

a decade perhaps? =.=

hahahha i almost laught till i roll on the floor. =.=
little flower? =.=
hahahah!!!!!

saddient look hot.
keep up the good work. =.=

its all the same la bro...
dont worry too much on small differences.